use SSL_VERIFY_PEER with the "always ok" callback,
instead of SSL_VERIFY_NONE with no callback.

The latter doesn't work correctly in wolfSSL, it accepts self-signed
certificates just fine (as in OpenSSL), but after that
SSL_get_verify_result() returns X509_V_OK, while it returns an error
(e.g. X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN) in OpenSSL.